A three-dimensional chemical transport model (CTM) is used to study the stratospheric ditributions and global budgets of the five most abundant isotopic analogues of N₂O: ¹⁴N¹⁴N¹⁶O, ¹⁴N¹⁵N¹⁶O, ¹⁵N¹⁴N¹⁶O, ¹⁴N¹⁴N¹⁸O, and ¹⁴N¹⁴N¹⁷O. Two different chemistry models are used to derive photolysis cross sections for the analogues of N₂O: (1) the zero-point energy shift model, scaled by a factor of 2 to give better agreement with recent laboratory measurements and (2) the time-dependent Hermite propagator model. Overall, the CTM predicts stratospheric enrichments that are in good agreement with most measurements, with the latter model performing slightly better. Combining the CTM-calculated stratospheric losses for each N²O species with current estimates of tropospheric N₂O sources defines a budget of flux-weighted enrichment factors for each. These N₂O budgets are not in balance, and trends of -0.04 to -0.06 ‰/yr for the mean of ¹⁴N¹⁵N¹⁶O and ¹⁵N¹⁴N¹⁶O and -0.01 to -0.02 ‰/yr for ¹⁴N¹⁴N¹⁸O are predicted, although each has large uncertainties associated with the sources. The CTM also predicts that ¹⁴N¹⁴N¹⁷O and ¹⁴N¹⁴N¹⁸O will be fractionated by photolysis in a manner that produces a nonzero mass-independent anomaly. This effect can account for up to half of the observed anomaly in the stratosphere without invoking chemical sources. In addition, a simple one-dimensional model is used to investigate a number of chemical scenarios for the mass-independent composition of stratospheric N₂O.