Service is half of your pension factor, and a purchase can carry you over a milestone (see one more year). Buying credit never changes your tier.
How part-time days turn into credit
| Days worked in a school year | Months of credit |
|---|---|
| 20-29 | 1 |
| 30-49 | 2 |
| 50-69 | 3 |
| 70-89 | 4 |
| 90-109 | 5 |
| 110-129 | 6 |
| 130-149 | 7 |
| 150-169 | 8 |
| 170 or more | 9 (9 months = 1 year) |
Handbook pp. 15-21; Tier 6 deck (2023) slides 15, 19-21
What you can buy
- After two years of member service credit you can buy credit for earlier NYS public service. Cost: Tiers 3-4, 3% of the salary earned then (Tier 4 plus 5% compound interest); Tier 5, 3.5% plus 5% interest; Tier 6, 6% plus 5% interest. Tiers 3-6 can't buy out-of-state service.Handbook p. 17
- With five years of NYSTRS credit you may buy up to three years of credit for active military service before you joined (RSSL § 1000). Each year costs 3% (Tiers 1-5) or 6% (Tier 6) of your salary in the 12 months of credited service before the calendar year of your claim.Handbook pp. 19-20
- Military service that interrupted your membership may be credited under USERRA (up to five years) or Military Law § 243 (up to four years). It's free for Tiers 1-2; otherwise it costs 3%, 3.5% or 6% of the salary you would have earned, depending on tier.Handbook pp. 19-20
- You can earn at most one year of service credit per school year (July 1 to June 30). Part-time and substitute work counts once you reach the equivalent of 20 full days: 20-29 days = 1 month, up to 170+ days = 9 months, which equals a year.Handbook p. 15
Military service before you joinedActive members, or members who retired on or after Dec. 21, 1998, with active military service before joining and at least five years of NYSTRS credit. Up to three years in total (with any military credit in another NYS public system), not more than net active service. The 2016 amendment (Ch. 41, eff. May 31, 2016) removed the specified-conflict requirement but did not let retirees buy credit.Handbook pp. 19-20
Military service that interrupted teachingUSERRA: up to five years, no minimum NYSTRS service, return within 90 days of discharge or by the following September. Military Law § 243: up to four years, return within one year. Cost: none for Tiers 1-2 (and Tiers 3-4 who had stopped contributing); otherwise 3% (Tiers 3-4), 3.5% (Tier 5), 6% (Tier 6) of the salary you would have received.Handbook pp. 19-20
Article 19 credit (Tiers 1-2)Eligible Tier 1 and 2 members get one-twelfth of a year of extra credit for each year of NYS service at retirement, up to two years, if in active service for at least 20 days in any school year on or after July 1, 1992.Handbook p. 21
Ask NYSTRS for the cost of a purchase in your case. This site doesn't compute purchase costs.
Questions
Does buying service change my tier?
No. Buying credit for earlier service doesn't change your date of membership or your tier. Only reinstating an earlier membership can.
What's the most service I can earn in a year?
1 year per school year (July 1 to June 30).
Source: NYSTRS Active Members' Handbook, Updated October 2026, pp. 15, 16, 17, 18, 19, 20, 21. Also: Tier 6 deck slides 15, 19-21. Last reviewed .